A new genus of tantulocaridan (Crustacea: Tantulocarida) parasitic on a harpacticoid copepod from Tasmania Geoffrey A. Boxshall Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Introduction There are now eleven described species of Tantulocarida placed in five genera (Boxshall & Lincoln, 1987). One of these, Basipodella Becker, contains two species both of which are parasitic on copepods. The other four genera parasitise tanaid, isopod, cumacean and ostracod hosts. B. harpacticola Becker was described from unidentified harpacticoid hosts caught at depths of 2000 to 5000 m in the Peru Trench in the eastern Pacific (Becker, 1975). B. atlantica Boxshall & Lincoln was found at a depth of about 3000 m in the North Atlantic to the southwest of the Azores, on a copepod belonging to the harpacticoid family Tisbidae (Boxshall & Lincoln, 1983). Whilst examining a collection of harpacticoids from the Bass Strait, off Tasmania, a single specimen of a Stenhelia species was found bearing a tantulocaridan on the side of its urosome (Fig. 1). This specimen, a tantulus larva containing a developing male, is described below as a new genus. Description AUSTROTANTULUS gen. n. DIAGNOSIS. Class Tantulocarida. Tantulus larva with first thoracic tergite partly concealed beneath posterior margin of dorsal cephalic shield; cephalic shield ornamentation comprising longitudinal lamellae and pores; thoracopods 1-5 of tantulus larva biramous, with well developed endites, uniramous leg 6 with coupling spines on protopod; abdomen of tantulus 2-segmented; adult male formed within trunk sac originating posterior to sixth thoracic tergite of preceding stage. TYPE SPECIES. Austrotantulus lincolni gen. et sp. n. ETYMOLOGY. The generic name is derived from the Latin australis meaning South, and tantulus which forms part of the name of the class Tantulocarida. Austrotantulus lincolni gen. et sp. n. TANTULUS LARVA. The body (Fig. 2A) comprises the cephalic shield, 6 free thoracic somites and a 2-segmented abdomen. The body length is 125 um, measured from the tip of the cephalic shield to the posterior margin of the abdomen, excluding the caudal setae. This may be an overestimate because expansion of the trunk sac may have caused separation of the thoracic tergites. The cephalic shield (Fig. 2B) is longer than wide (47 x 32 um) and tapers anteriorly. The rostrum is absent. The oral disc has a diameter of about 1 5 um and is positioned anteriorly so that it is visible in dorsal view. The surface ornamentation of the head, as seen by light microscopy, consists of longitudinal lamellae dorsally and oblique lamella on the downturned ventrolateral margins. Associated with these lamellae are at least 5 pairs of pores, as marked on Figure 2B. Internally a pair of chitinous bars leads towards the central pore of the oral disc. The cephalic stylet is very slightly curved and is about 22 um long. Bull. Br. Mus. not. Hist. (Zool.) 54(6): 271-274 Issued 24 November 1988
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